Nimbuzz Android app has been updated. The update comes with Push notifications (for Android O.S. 2.2 or higher), and message delivery notifications. The push notifications feature allows you to appear online to all your friends even if the application closed. The benefit is the battery will last longer and will be less data consumed.

The new message delivery notifications will display 1 check mark when your message was successfully delivered to the Nimbuzz servers, and 2 check marks when your message was successfully delivered to the person you are chatting with (though this does not indicate that your chat was read by the other person but only delivered).
To enable push notifications go to: Settings->Notifications-> Enable.